Electric switch gear



Dec. 25, 1934. J. CHRISTIE Er AL 1,985,653

ELECTRIC SWITCH GEAR Filed Oct. 27, 1932 5 Sheets-Sheet l m m5 QQ A@ NQ NQ w NQ 00% 4.. 9% buwbov 1 Nv@ w T .mw

Dec.` 25, 1934. 1. CHRISTIE Er AL ELECTRI C SWITCH GEAR Filed Oct. 27, 1932 5 Sheets-Sheet 2 Dec 25, 1934- J. cHRlsTlE Er AL 1,985,653

ELECTRIC SWITCH GEAR Filed Oct. 27, 1932 5 Sheets-Sheet 3 Dec. 2.5, 1934.

J. CHRISTIE Er Al.

ELECTRIC SWITCH GEAR Filed Oct. 27, 1932 5 Sheets-Sheet 4 wf A EN DeC- 25, 1934- J. CHRISTIE ET AL ELECTRIC SWITCH GEAR 5 Sheets-Sheetv 5 Filed Oct, 27, 1932 au: lea

Patented Dec. 25,` 1934 iii; eUNVH1l y STATES PAfriilvlf.r

of Great vBritain auskennen oeteser- 2v, 1932, serialize; 639,525 j n In .Great Britain November "l, 1931 f 27 claims. (ci. 17e-:75nd

This invention nemesio electric swiiehgeerf, for instance. vas metal-clad switchgear, and

` is especially concerned 4with interlocking mechanism for preventing lncornect operation of the switches. tormmgpart. ci!k the gear. Thus for example in a duplicate 1busbar`metal-.clad switchgear v'layout for a v'high voltage electric power station, whereinreaeh oils-immersed circuit-breaker islprcviflerl with three isolating switches, controllingzthe connections 'of its terminals tothe twoilbusbars and lto theeable or .other incoming or outgoing circuit with or without further auxiliery' switches. for .earthing the cable and for `controllir'igthc connect-lontola potential transformer, it will be realized that it. is of importance time belrobust andsimple to'understand and to manipulate. i f The' an'angement according tothe .invention comprises in 'combination with a group of'actuating levers respectively controlling the Aopera'- tion'of the associated switches, a longitudinallymovabley selector bar provided with slots or pro- Sections which cooperate with slots or projections on the actuatinglevers or on members connected thereto in such @manner as to prevent operation stony ol' ther-levers unless thc'selector bar has previously becnf'moved' into a position appropricte to such operation and to prevent movement of the selector bar into any operative position unless the actuating levers vare in a position appropriate to. such movement, Thus interlocking mechanism ,for the isolating switches or other auxiliary. switches associated with. a main circuit-breaker or group of circuitbreaker. may cQmpriSe a common shaft on` which 'actigatingg` levers for the auxiliary switches Aare pivoted, a `selector barQdlsposed parallel to the shaft and provided with slots or projections cooperating w'ith slots or projections on the actuatlevers ormembers Iconnected thereto; and preselecting means iler moving `the selector bar longitudinally, the' arrangementl of the slots or projections being such that before-*any the y leverscan be operatedthc selectorbar mustrst be v movedV into -a position :appropriate to rsuch lever 'opera-tion and that: the selectorba'r cannot be moved into the selected position unless the auxiliary switches :are vini-acondition appropriate tothe selected operatiung.4 are preferably provided whereby .the selector baror ,an additional locking bar associated with.V the preseleoting means acts `to preventeciosing of the main circuit-breaker for citant-breakers unless the auxiliary switches are ina condition appropriate to such closing;v the' arrangement being such that the selector bar remains locked against movement so long as.. themain vcircuit-breaker or, circuit-breakers are-closed .ux fr Y Means may also :be provided whereby. the selector bar prevents `lowering of. a `tank containing a circuit-breaker or, other, apparatus assoe ciated with the switches .unless the-switches are in a condition toisolate'such apparatussff'lhis may conveniently be eiected by controlling the supply of electric power for the operation fof' the craneor other tank-loweringtdeviccby means of a switch or .coupling whicl'i'can only? be engaged when. the` selector bar is'in 'the-appropriate'. position. An inverse' interlock 'mayalso be obtained by clotting:` the selector bar-.Vor an interlocking bar connected thereto to receive a spring-pressed plunger, whichengages in theslot` and prevents movement of the selector bar sc longas the tank is lowered. A

.In aconvenient practical construction each actuating lever has a segmental extension provided with shaped peripheral slots. respectively lying in the `path of the selector bar in .the operative positionsof the actuatinglever, whilst the selector bar `is .provided with transverse slots to permitthe actuating lever to be moved from one operative position to the `other. when the' selector bar isl in theiappropriate position/and also with longitudinal'ribs cooperating withthe` shaped peripheral slots in the Vsegmental extensions of the actuating leversto permit or prevent longitudinal movement of the selector bar inaccordance withthe positions of the acti'iati'ngil'evers.` Theactuating leversl and the selector bar ymay be directlyoperated by hand or may beecontrolled electrically (for Yexample from a remote point) or alternative manual and electrical controls may `be provided. For the purposes of electrical control (with orl"without `alternative hand-control) f two reversible1 electric I motors may be providedon'e Aof which drives the selector bar for preselecting purposes whilstthe other-is between the existing position of the selector bar and the desired new position thereof and to stop the motor when the new position is reached."

Each actuating lever maybe operated by the executive motor through a disengageabl'er actuating device controlled by movement of the selector` bar, and in one convenient practical arrangement the executive motor and a shaft driven by the motor and carrying the driving members of the actuating devices vare themselves carried by and movable with the selector bar. J

The invention may be carried into practice in various ways, but the accompanying drawings illustrate some convenient practical arrangements according thereto,'a's applied to the control of i the isolating and other auxiliary switches associated with a main: oil-immersed circuitbreaker or group of circuit-breakers in a high voltage switchgear layout; In these drawings,

Figure lis a diagrammatic perspective view of one arrangement of interlocking mechanism for manually-operated control gear,

Figure 2 illustrates a'further interlock associated with the arrangement of Figure 1,

Figures 3-8 aredetached views of parts of the mechanism of Figure 1,

Figure 9 isaI perspectiveview of a preferred arrangement of interlocking mechanism for manually-operated control gear,

Figure 10 illustrates diagrammatically a modication of the arrangement of Figure 1 to permit alternative manual and electrical control,

. Figure 11 is a detailview of part ofthe arrangement of Figure 10, and u Figure 12 illustrates diagrammatically one form of switchgear, for which the" interlocking mechanism is more'especially intended. Although the interlocking mechanism according to the invention is applicable to other forms of switchgear, it willbe assumed forv convenience of description that? thev switchgear controlled is arranged in the manner shown :in Figure 12, and a brief description of the main relements of this switchgear will rst be given.

'Ihe switchgear illustrated dlagrammatically in Figure 12 consists of a three-phase unit comprising three main oil-immersed circuit-breakers each controlling the connections from duplicate busbars to a feeder cable in one phase. The apparatus in each phase is identical 'with that in the other phases, but in order to show the elements more clearly, parts have been broken away to'show sectlons'ontwo parallel planes'in the right-hand two' phases in the drawings.v The'apparatus in each phase' comprises an oil tank 400 for the main circuit-breaker, having two busbar chambers 410, 420 mounted above it, the two busbars 411, 421 respectively passing through these chambers. Two withdrawably mounted conductors 412, 422`extend fdown respectively from the two chambers into the circuitbreaker tank 400, where they both make connection with one of the main circuit-breaker contacts 401, the arrangement being such that when one of the wlthdrawable conductors,'say'422, is in its lower operative position, its upper end makes connection through an isolating switch 423 in the the withdrawn conductor.

chamber 420 with the main busbar 421. A similar isolating switch 413 is also provided in the chamber 410 between the reserve busbar 411 and the withdrawable conductor 412. Each withdrawable conductor is mechanically interconnected with its isolatingswitch, sothat the opening of the isolating switch takes placevsimultaneously with the withdrawing of the conductor, and an earthed contact 414 or 424 is provided whereby the isolating switch when open earths The three isolating switches 4l3 for the reserve busbars are operated by leversinterconnected by a link 416, and the three isolatingswitches 423 for the main busbarsr aresimilarlygoperated by levers 425 interconnected by a link 426 'I'heothercOntact v401 of the main circuitbreaker is also connected through a withdrawable conductor 432 and an isolating switch 433 in a feeder chamber 430 to the feeder cable 431. An earthed contact 434 is provided in the tfeeder chamber for earthng the withdrawable conductor 432 when the'isolating' switch isopen. The three isolating switches 433 forrthe cables are operated by levers 435 interconnected by alink 436. i

An oil-immersed .potentialy transformer 4440. is also provided "in each phase by the side of the main circuit-breaker*tank'400' and is connected to the cablecontact .in the feeder chamberl 430 by meansof a withdrawablef'fuse'441 and an isolating switch' 443 provided -with an earthed contact444 fore'artlii'ng thetransformerwhen the switch is open. This isolating switch is operated by'a lever 445, thethree levers-being interconnectedbyalink446. i :i A'further auxiliary' switch 450 Ais provided in each feedercha'mber 430for earthng `the cable, this switch being operated by a lever 451. The three levers.' 451 may be connected together lfor simultaneous operation, but (as will-be mentioned later in connection with Figure 9) it is often d esirable to provide means for earthng one of the phases ofthe cable'in advance ,of thel other two phases'. The levers 451 in the two phases shown on'the right-'hand siderin Figure l2 are-therefore interconnectedby a link` 452 but are `operated independently of .the lever 451v for theremaining phase. The arrangement of Figure 12 is shown more especially in association withy the preferred interlocking mechanism to be described later with reference -to-Figure 9: and the various isolating and auxiliary switches are operatedby the links 161,171, 181, 191,221 Vand 226,'the ends of which arefshownin Figurev 9. A. generally similar arrangement of operatingy links-is employed with the arrangementof.Figures` 1-8, the links 161, 171, 181, 191 (respectively for the' potential transformer isolators; the cable isolators,` the' reserve busbar isolators andthe main busbar isolators) being replacedl by similarf'links 61, `'71, 8l, 91, whilst the two links 221, l22S for the cable earthingswitch'esfare replaced'by a single link 5l:

The contacts 401, 402 of the three main 'circuitbreakers are operated vsimiiltaneously by levers 403 interconnected by a link 404 which is 'connected through la lever 405 to a main 'operating solenoid housed in a casing 406. TheI solenoid operating mechanism is interconnected r(as more fully vdescribed later with reference lto Figure 9) with the main interlocking. mechanism for the auxiliary switches by means of the interlocking rods24o,245..

The interlocking mechanism according yto the invention will now be described. l,

arrangemeritY;Foi*` lligures.- 1-8rtheA five actuating leversopsu', 16,480,911 are arranged xriovalile through :asright angle'into their fon positionsi llhelevers'are arranged `for dihandt :operation are connected to the operating, mechanisrnffonthe associated switches thlbughslinksf i'ndcatedwat 51,61, 7l, 81;. 91S 'Immediately beneath and parallel to the common shaftfs, onywhich: the leversare mountedfis a lselector bar100 which can be` moved longitudiriallyvintdi any-fone of fivepositionsm Each. actuating-lever has-:a segmental extensionf52 or 62; or on 825101#v 92fbeneathlthe shaft: V4:01. extending into' vthe pathfoff the selectorwbar .100, -and the iterlockmg.: of` theV levers 'is'. eiected. by means of slotsiand-Hprojectionsrin.the selector bar and in the'rsegmentalfextensioms: ofthe levers.. ..LI'heiniovement otpth'e selector barA 100 is conrollledf byralpreselecting handle lOLcarrying a springs-loaded catchIOZ which'can engage in-any one; offiivenotchesin.` aii'xed part 103.015.: the

framework, ofthe mechanisxm4 this handle preterablyicarryin'g: avpointmlM cooperating With suitable markings onvthe :cover of theV frame-Y workitoindicate. the position Aof the Vselector bar tooffandj if=desired, also the switch: .operations which can.` be performed.inrsuchzfposition- A ITh'e arrangement ofthe slotsrand; projections novv be .described with.l .reference-` partly-.to Figure 1 and partly to Figures-Iwhich respeca tivelyE show s theA fiveI actuating; r. levers together with :the associated parts "of theseleotor bar; the lever idealen-Tease. being' Ashowrrsimoedv apart from the selectory bar-1inI ordertoashow the -slots `and. pfojectionsmorer clearlye."` For convenience, Figare: also: marked.f.to..indicate therffive positions ot the`1selector .bar; .As-will be: described irrr detail,` the 'I seg-mental :extension onz eachlever hasia"` peripheral slot.l at: its ilowermostppoint with--Y in: v.which the.' selectorr bar .lies when the lever is ix'iits'o positionvand'jtheyextensions on.4 three oi. th'eileve'rsalso have peripheral slots` within which tle'selector barles when the leversware in their onpositions. f l n f 1 'The first position'of theselector bar 100, shown inFi'gure Igi is allocated to cahle earthing. For this purpose the selector barbas 1a transverse slot 105:(se`e -Figurem` which lies ropposite the cable -earthin'g switch lever: 50ewherr the bar is inthe mst position; "thus enabling this lever to be op` ersted` 4insthisf.' position. The absence of: other slots in this partof the selector bar prevents op"- eration of the cable earthing switch. lever-in any othenposition'of the bar; Theperipheral slot 53 inthe extension 52. of this' leverA permits movementof the selector bar into anyof the five poe sitio'ns; so llong as the. leveris in its. oi position, butfwhen 'the levenhas .been moved toits on position, `the absence' of allsecond` peripheral slot preventsmovement ofthe selector har away' from tfliefrstposition.` 'f l LVThe potential transformerlisolator lever o0` (see Figure 4)` pcannot be loperated in the rst 'selector lafposition, `but can kie-operated" in anyot the other four positions, and for'thispurpose theselector 'bar is provided witha transverse slot 106 oflfour tim-es: thel normarwidnh. Thus whether thefleverG'O is inl its on' or its on," positionyit will not" prevent movement `015' the selector bar 100fbetweenthe second' and' fif-thfpositions; but since the? extension `62 on the lever 60 has one peripheral slot 63T only, the selector bar'cannot bei moved into.l -Athe `ilrst: position unless? the'. lever- 601A is in itsoirposition.v i ,f

Al transverse-slot -107 (see Figure 5)-isn` thaise; lector` bar 100 lpermits operation-f'ofthe'cabie isolator lever :in. the second positiononlvthis l? lever being-.locked against operationin all other positions. Ther segmental extensionn72fot the leverV 70f has two peripheralu'slotsn'lii, 'Hf which are stepped -and of different; shapes, '-the slotl 13 Y having a' deepened portion' 7:50011" one side. and

the slot 'Mia deepened portion 76lon `thepthel: sidei'Theselector bar 100 is provided with. upstandirig longitudinal.E ribs` 108, 109 'to` suit; the shapes of these slots. Ihe..rib.1t08` lies opposite the lever 70 whenI thezbar is in the. iii-st.: position and. ison the front'half ofthe bar; thusrcbrrea spending. to `the deepened. part 75fof..the:.om s1`ot73r in thelever; The rib `109; is three-.times the length. of the rib 108 and sliesifoppositethe lever Fmi inthe third,` fourth Land hith.. positions of thebar. f This rib 109. is on theV back half ofnthe bar and corresponds to the. deepened.. part 76 ot the on'slot 745m the` lever.` `Thus. infthefsecond position ofthe bar 100', the `lever 70 cantbe moved `from. one position toi ther-other.. `If .itxis movedl tothe 0E positon,=:the selector barxcan be moved:to.the.rst position but not to the. third; Ifhowever the'leverv'TOwsmoved to: its on position, the bar' .i100..canriotihe` moved to the rrst :position but can be moved-to .the'thirdl fourth andlnfth positions. `In order `to economize space, the port offtheselector bar cooperating with the lever 'lof in the. fifth position; is` the same.; as:. that; `cooperating: withv the'` lever `60 in `the yiii'st position and r:;the=slot. 63/l inthatf leveraisconsequently stepped-.rta fisiche llongitudinal rileA 109;-on.. the se l'efto'i."br;t1 1121121? L 'f The segmentali extension 82 on, s the.` reserve busbar "isolator leverff'80 tseefFigure 6') has `ai stepped slot 83 cooperating wtihtthe selector bar 10o in the. off positionof thelever'ancla4 plain shallow slot `8i cooperatingzwithl .the selectorzbar infzthefon position, the deepened portion 85.` o! the slot 83.-bei`ng: arranged :to` suit-the rib." 108 on thefselector. bar and alsoranotheryrib 110=onthat bar; Here again the same :partot thefselector-bar is utilized both for theith positionfornthe.- lever 804 andzfor the rst position for the lever 70.. A transverseslot 111 is providedin the: seleotorlbar.

which .enables the lever to bepperated inthe third position of the bar. solang ls-the reserver busbar isolatoriever Sois-in itspof! positionthe; har 100. can befreely moved to anymsition, whilst whenlthis; lever-ismoved toits onl position in the `third positiorriofthe; bar; `the* bar can be moved to the fourth position but not, the iifthor` to the-second position.V 'r- 1- i -The mainbusbar isolaton'lever` 90 (seefFigure 7). isxsimilarA tosthe levert80 and has a,.stepped slot 93 and a plain shallow.' slot:` 94. l .f The: deepened portion of the slot 93 cooperates withn a longitudinalrrib 112 on the. -selector bar 100, 4this rib being. long enoughto lie opposite the lever 90 in thefirst three positions ofthe bar. AV transverse slot 113.in the bar. provided .to permitoperation 0f ,the lever 90 inthe fth position only. the lever` 90 isfmoved to the on position, the lselector` bar. can he moved tothe fourth but netto the third position, the bar 4being 'freely movableto any position if the lever 90 is inthe oi position.

Thus inthe first positiohpf theselectorv b'ar thecable earthing switchlever 50-`rnay`e operated but the other iourleversfae locked oiI,` In the second position the potentialtrans'former isolator lever 60 and the cableisolator lever 'I0 can iboth bev operated ibut the 'other three levers are locked off. In the third position the potential transformer isolator lever 60 and the reserve busba'r isolator lever 80 can be operated, the cable isolx'tlox'leverV .70. is locked on and the other two levers 50, are locked off. In the fifth position the potential transformer isolator lever 60I and thel main busbar isolator lever 90 can be operated, the cableA isolator lever 'l0 is locked on and the other two levers 50, 80 yare locked on. In the fourth position the potential transformer isolator lever 60 canV be operated, s the cable earthing switch lever 501s locked oil and the cable isolator lever '10` is locked on, whilst the two busbarisolator'leversBO, 90 may be both' locked on or either one locked on'- andl the' other locked off. Ity is however impossible for bothv busbar isolators to be closed at the. sametime. This fourth position is utilized for-operation of the main circuitbreakers and? a further' interlock is also provided in' association Vwith the actuating lever forthe main circuit-breakers. 1 f

"fThisfurther interlockmay take various forms, but must be such' as: to prevent1 closing of the main'circuit-breakersunless ther selector bar is inI the-first or in the'fourth` position, and to prevent movement of the selector bar from such position so long as the` circuit-breakers areclosed. Inzthe arrangementv shown .in'Figure 1 and also in Figure 8, the selector bar =has two transverse slots 114 and 115, which in the first and fourth positions respectively of the selector, bar permit. movement .ofaf further hand leverl 120. This lever has an operating link.121 and a segmental vextension 122? provided with a singleperipheral slot123, the lever thus beingidentical in construction with the cable earthing switch Ilever 50." The slots 114, 11S-permit the lever 120 tcbe moved to the' on position-iinthe first and fourth selectorrbar positions, but the lever is locked in the f'off position inthe yother selectorbar positions, whilst'the selector bar isv locked against movement so long as'the lever 120 isi'nithei onfipositlonl "This lever 120 may directl'ycontrol the closing and tripping ofthe main circuit-breakers through the'flinkl21 or may be'inter-connected mechanicallyfor electrically with a separate circuit-breaker operating fdevice. Thus for instance in the caseof circuit-breakers closed by means of a solenoid or motor, the'. lever 120 may operate an auxiliary contact in the energizing circuitthereof-or may actuate a tripping device associated therewith. An alternative form of interlock for the main circuit-breakers will be described later with reference to the preferred arrangement of I"igure9.'-

'I'he movements of the' selector bar 100 are also utilized (as shown inFigure 2) to provide an interlockfwith the lowering mechanism 'forthe main circuit-breaker and potential transformer oil tanks. -For'this 'purpose the `selector bar 100 is' mechanically coupled through a lever and link mechanism 131 to an interlocking bar 130, which passes across thetop-plates v132 'of the circuitbreakery and transformerltanks 133 in the three phases, 'the' arrangement being such 'that the interlockingbar 130, and ,therefore also the selectorbar `100,15 locked against movement when any one of the tanks 133 is lowered. A similar interlock fis also employed inl ithe preferred arrangement illustrated-in Figure 9, whereindetails of ythemechanism vconnecting a itank and the interlocking bar -are shown. Thus the topplate132 ofthe tankl33 containsa robust plunger 134 pressed downwardly by a spring-135k against the'fiangeof thetank. The plunger' 134 passes through a longitudinal slot 136 in the interlocking bar 130 and carries ay crossbar' 13'14 which lies in a transverse slot 138 in the bar 130 when the tank is lowered. Thus when the tank 1331s in its normal raised position the crossbar 137 lies clear of the slot 138 and leaves the interlocking bar 180 and the selector bar 100 free to move, the bars being locked against movement when the tank is lowered. Inorderto prevent lowering of any tank except when the selectorbar 100 is in the rst posi-I tion,the selector bar carries a plate 140 which covers` the fixed socket member141 of a plug and socket connection in the energizing circuit for the electrically operated crane or other tank lowering mechanism, the plate 140 having a hole 142 so arranged that the socket 141 is exposed to permit insertion of the plug 143 when vthe selector bar 100 is in the first position. Thus it is impossible to energize the vcrane rfor lowering atank unless the selector bar 100 is in its first position, with all the actuating levers except the cable earthing switch lever 50 locked oiI, and moreover the selector bar cannot be moved from this position unless all tanks 'which have been lowered have been lifted again into their normal operative positions; As has been mentioned the main circuit-breakers can be operated in this position, and this facilitates inspection of the circuitbreaker contacts in movement with the tank lowered, if desired.

It will be vappreciated that vthe particular arrangement of interengaging slots and projections may bexmodified in a variety of ways. Thus for instance it may in some instances be more cori-l veni'ent to mount the selector bar at some distance from the actuating levers, and to provide longitudinally movable links connected to the levers 'for interlocking purposes. It will readily be seen that anfinter'locking system performing the'zsame functions as that above described can be obtained by providing a projection on each link which cooperates with suitably arranged transverse and longitudinal slots in the selector bar.

In the foregoing arrangement each lever li'as been described as effecting simultaneous operation of the correspondingswitches in the three phases. It is often desirable however to operate the cable earthing switch in one phase in advance of those inthe other two phases in order to. minimize disturbance if the cable should happen to be alive. Provision is made for this' in the preferred arrangement shown in Figure 9, which will now bedescribed.

f yIn this arrangement nve 'hand levers 150, IBO. 170, 180, 190 are provided, which are generally similar to the levers 50, 60, 70, 80, 90 of the arrangement of Figures 1-8. 'Ihe cable earthing switch lever is in this instance fixed on a shaft 155, on which the other four levers are freely mounted. Theinterlocking between the levers is effected by a selector bar 200 mounted beneath the shaft 155, thisA bar being movable longitudinally into any one of ve positions under the control of a pre-selecting handle 201 pivoted at 202, a spring-loaded catch (not shown) generally similar to the catch 102 shown in Figure l, being provided to locate the selector bar properly in itsivarious positions. The handle 202 carries a plate 203 having a hole 204 through which a plug 205 can be inserted into a socket 206 when the bar 200 is in its rst position but which prevents insertion of the plug in the socket in any dthe'r-:seletor bar'; position; xthe 'plugandfsocket controlling Afthe' v energizing :circuit for energining the rraising and loweringwdevice aforfthefcircuitbrm'kernnd .potential .transformer tanks. f c is emdipotentialfftransonner isolator .lever 16 operating link161' and :avsegmental exten.

sion-I 162 `with n.1 single, peripheral :slot 163. `This lever cooperates .withe transverse s1otx207 in the lectorffber's200, thelslfot 1207 'being offfsuch `a length as. topermitvoperation of the lever `in the thirdi-Iourlth .'.andmfth positions :but ynot :in `the rstsendrsecond positions of fthe selector bar.

` -.fl'hecable isolatorllever 170 hasfanoperating link L'llndlaz; segmental.` extension :172 with two pe-r the fourth position- .Thusythe `lever 170' is locked,

i: oitinltheirst .andsecondpositions of the bar and canvibe .operated in'theythird or in the liifth DOSiOn-butwnotl in the. fourth position.` The .1

shallow slot 174 in Vthe :lever-is deep. enoughto allow the-.bar tobe moved Ainto the fourthposition when fthe leverde in its on position but` prevents movement of I:the-fher tinto;4 thersecond andwrst positionsjllnlessthelever isdn-the off position. 'l'.hegleven1170 also :carries-:em` armf175 extending tuoi-ossv the; path of; the two busbar -isolator :levers 18o-190,- soE-thatfneither'busbarlevercan be -moved 'to...i.ts.on..fposition unlessthe cable isolator lever 11W-.ha moved? to aitsnposition, ,.an'd the deep peripheral; .Slot- 18310r r1.93@ ondeJ 'Shallow f s1ot;1`84 or..19fi respeotively operative SJsQtQr ber 200th@ adeep slot 2.11 and s. Shallow l slotr 1-2 respectivelyopposite the reserve-busbar the.thirdlandffourthgpsitions of the han @edelen eshalwwwwl `and weer Slot.

'21.4. respectively opposite fthe main busbar lever the. olrthfandth Qstiensoff the bar.

' nthethirdfpositqlithe levers 160, 170, be Operetdeedtheleverlflis locked inthe .ith-Rgsition. the levers 16 0,. 170, 190

cette @goed andthe ieverio 1s-locked off. In

the 'ftourth Vpositiorythe .lever 160 can Ibe operated amusement@ namelvvwith the'three levers 651.) fwfi-llthe.notifiezlfthetf.the4 arrangement of the tlig'eelevers `130.180,190,is,suhnsnot to require the pro hier; Lof. especial-selector ter` position 1y .thelssgeedlmsitien in. .the arrangement otre 70? @versand this. enables ,both the afstand thesecdnevositions mbe` .leed `f. .r.. :a.b1e earning..

thesecond poslwnfbensutilzed `ffnmeeutthine one phasefgndythefrst position `for earth/ing the other setlist thegone phaseyis. earthed in ad- 75 vement other. brthertimeinterval requirente.

with the levers 170, :180; on and *thev lever` helevers 170, 1,905V onand the lever Vgell-1Ds Ier: thefoperetienl of the 'cablek move fthe :selectorfbar from the second lposition to the; rstrr; `It is` preferable .to l employ a' `single control lever 1:150 .for reiecting `eorthing:inthe proper sequenceofthe'three phasesgandin `the arrangement `illustrated 4this lever is :movable .from `the ott' position `intota. mid-.positioninxthe :second selectorlbar.. position and from :the mid-position into theffull on postion'in the'nrstiselector bar position. For this .purpose tlie segmental extenm'on 1510i theleverl has a deep slot 'lz'which cooperates with the Vselector bar `.200 zinithe of! position and `eshellow slot 153 cooperating with the bar inthemidfposition. vThe selector bar has a. deepslotl` opposite the lever in the first position and a shallow slot `216 'oppositethe .lever in the second position. .A vlateral `projection 154 is also provided on the lever between `the `slots 152, 153;:which Valouts against .the 'iside-of lthe l selector bar rbut can Lpass through the'slot215 inthefbar whenthelbarisrin thesecond position.`

Thus, .assuming .that the lever 150 *is .in .its `ol'f position, the projection 154 holds it locked 'in 4the off position unless the `selector bar2`00 is moved to thesecond position. -When the bar isin thesecond position'lthe llevercen be moved to itsmid-position therdepthof fthe slot216 allowing-thismovement and Apreventing -further movement. The selectorbar can now be-moved-to the ilrstposition, the projection 154 now lying on theotherside oi" the bar.: and-when' therstposition is reached the lever `cam be movedlto its full on position, in `which it lis shown in Figure 9;

'The lever 150 doesnot' itself dlrectlyoperate the cable earthng switches,` the- Aopereticrn 'of nthe switchjin` one phase being -eiected 'through `a. link 221 -lby A'ei-bifecket 220 `p'ivoted at2223thisbracket carrying a. pin 223 with which' afcm 156-fon the shalftl engages. The operationrof'thefswitches in the Vother-@two phases is similarly effected throughs; link 226 by 'a bracket 225 pvoted at 22'? `and'"corr-'ying a'pin 228-with which afcem 157 on the "shaft 155 engages. The twolcams 156, 157

arefso'shaped that movement of the'lever 150 from the oir position fte the mid-position operatesthe bracket`-220 ndcauses one phase to be venrthed, whilst subsequentmovement of thelever -150 to thefull on `position operates the bracket'225 "and thus earths the other two phases.; `It will be noticed thatinthis arrangement thesecond selec-V tor bar position is wholly reserved=forfsinglephase cable earthing, and thatthe other operations associated with theiflrst 'selector bar position in the arrangement `of Figures 148 `are `still reserved for that position.l Then-operation `of lthe main circuit-breakers may 'be effected in a manner analogous Vto that employed Vthe arrangement of AFigures 1-8, or alternatively. 4as shown in Figure 9, by means of a. longitudinally-movable locking `berv230 held betweentwo notched verticalrods 240, 245. The notched `rodl 245'V is connected through `a llever mechanism 246 to thepreseleoting handle 201 in such :manner as to be moved up enddown` in accordance with the longitudinal movements of the selector bar 20o, and has two notches 247 and 248 which lie opposite one endfof the lock-l ingbar 230 when `the selector bar'is in itsilrst and fourth positions respectively. The other notched rod 240 has a single notch 241 and is connected to a shaft 242 forming partof-thelclrcuit-breaker closing mechanism, the arrangement being suchfthatthe notch 241 lies opposite the end vof thelocking bar 2304 when the circuitbreakers areopen. The length of the locking bar 230 `is `such that yearch .notchedrod .is locked by the engagement of thebarin a-notch,'unless there is afnotcliV opposite. the.. other endoflthe locking bar.` yThe ends ofzthe locking bar 230 may be so shaped that; the bar vis moved longitudinally by verticalmovement of veitherlnotchedrod 240, 245 provided that the other notched member vis inra position to allow such movement,y or alternatively means may loe-provided for moving the locking bar by hand.` In the example-.illustrated thev locking bar 230 isl normallybiassed ytowards the notched rod 245 by a weight 231 carriedby a lever 232-on` one end -nf which isa shaped slot 233. Engagingin this slot'is a pin 234 on a trippingrlever 235, pivoted at 236, this lever carrying .a vroller .237. cooperating with a part (not shown) of thescircuit-breaker closing mechanism, such `for .exarnple as a toggle device, the arrangement being such that when the tripping lever 235 .is raised the circuit-breakers are tripped and it is impossible to,closethecircuit-breakers without first lowering the tripping lever.

.Thus when the selector -bar 200 is inthe first position,v as shown, v`the weight 231. holds-the locking bar 230 in engagement-with the notch 247 inthe rod 245 `andthus leaves; the other notched rod240. free tobe moved. The circuitbreakers can now be closed by loperation ofthe closing mechanism and this will cause the rod -240 to movev vertically. vertical movement ofl the rod240 will lock the bar 230 in engagement in the notch 247 and will thus prevent movement of the selector bar 200 away frornthe first position,solongy` as the circuit-breakers are closed. Tripping of the,-circuitbreake rs will cause the r od`240to;be brought back to the position shown on the drawings withthenotch 241, opposite :the

end of thelocking bar 230.` releases the selectorgbar200 andmovement of thebar into the second position` will cause the notchedrod 245 to move down and thereby to move the locking bar 230 into engagement inthe notch 241, thus lock-p ing the rod 2 40 against movement, yAtthe same time the movement of thelocking bar 230 .will raise the weight I23,1 .and swing theslot 233 over,

thus raising vthe pin. 234 andthe ltripping levery 235 vand preventing operation of the circuitbreaker-closing mechanism. LThe circuit-breakers will thus4 be lockedppen until the selectorl bar200 is moved either.` into the fourth positionV or .backl again to, the first position, when the weight 231 will move the locking bar 230 to release the rod 24o-and willat thesame time allow the tripping lever .235.tofall to permit closing of the circuit-breakers.

, The arrangements above described provide only arrangementoLFigures*1-8 to permit such 'al-y ternative manual or electrical control.

4In the arrangement of Figures 10kandn11, a reversibleelectric motor 250 isprovided for moving the selector bar 1.00 for preselecting purposes, and

asecond reversible electric motor 280 is provided for executive purposesrnamely forr the operation of the actuating levers. I

. The preselectingmotor 250 on theselector bar 1.00 through a slipping clutch 252 land. worm reduction gearing 253. The ener,-`

gizing circuit of the motor 250 is controlled partly by a contact` device operatedby` the selector bar.

ldrives a rack l 251 100 and 'partly by a selector switch at the contro! point;A '.In a simple arrangement Vthe selector` switch consists of a selectorv arm 260, whichcan.

be moved into contact with anyone of vfive ter.- minals connected to flve pilot wires 261-265. and a key 266 for connecting the contact arm 260 to one pole 267 of a source Aoi' current, the other pole 268 of which is connected to the motor 250. The.. other ends of vthe five pilot wires are connected. respectively to five ixed brushes 271-275 which.

can selectively engage two contact plates 276, 277 mountedk on an insulating base 278 carried by the selector bar 100, the two contact plates 276,

277 being so connected to the motor 250 that the' direction of rotation of the motor depends which of the contact plates is in circuit. The arrangement of the contact plates 276, 277 is such that when the selector bar 100 is in the flrstposition, the first brush 271 is insulated and the other four brushes 272-275 engage with the plate 276 for driving the motor 250 in the forward direction to move the selector bar 100 towards the nfth position; when the selector bar is in the second position, the second brush 272 is insulated andthe third, fourth` and fifth brushes 273, 274, 275 engager with the forward drive plate 276, whilst the first brush 271 engages with the reverse drive plate 277; in the third position the third brush 273 is insulated, the fourth and fth engage with the forward drive plate 276 and the first and second with the reverse drive plate 277; and so -on for the other'selector bar positions. Thus. for example, if the selector bar 100 is in the second` position and the selector arm 260 at the control point is moved to the fifth position and the key 266fis operated, the motor 250 will be energized to 'drive the selector bar 100 in the forward direc-7 tion until the circuit is broken by the disengagement of the fth brush 275 when the nfth position is reached, assuming of course that the actuating levers-are in a condition to permit movement of the selector bar from the -second to the fifth position. If, however, the selector bar-100 is locked, the clutch 252 in the motor drive will slip. This clutch 252 may be arranged, if desired, to break the motor circuit as soon as it is caused to slip. It will usually be desirable to provide an indicating device at the control point to indicate theposition occupied by the selector bar 100 so that the operator maybe informed whether the selected movement has been eilectedor whether the clutch 252 has slipped owing to the locking of the selector bar by the actuating levers.

The executive motor 280 is carried by the selector bar 100A so as to be movable therewith.y

This motor 280 is connected through gearing 281 to the driving members of a main dog clutch 282 and anauxiliary dog clutch 283, which are operated together against the action of a spring 284 by a solenoid 285 so that the two clutches cannot be simultaneously in engagement. The driven member of the main clutch 282, which is normally engaged, is connected through gearing 286 to a shaft 287 running parallel to the se-v lector bar 100. 'Ihis shaft 287 vdrives actuating devices for the four actuating levers 50, 70, 80.

90 controlling the cable earthing switch, the cable isolator and the two busbar isolators. A similarr actuating device for the potential transformer isolator lever 60 is driven by a second shaft 288 connected through gearing 289` to the driven member of the auxiliary dog clutch 283. Two actuating devices are provided for the circuit-breaker lever 120 one driven by the shaft 287 and the other by the shaft 288, these devices being respec- 3 disposed parallel tothe shaft, preselecting meansk for`= movi-ng the* selector .1 bar longitudinally into any l'of ia numberof positions, vand cooperatingv slotsandproje'ctions on* the'selector bar andthe actuating levers which act to prevent .operation of 'any of the levers unless the selector I.bar isin,

motor ;280.to.1drve-theshaft 287; to, close the main busbar isolator, and subsequent depression ofthe other closing push.325 causesthe execue;

tive .motor v-iso .drive the shaft-288 -to close the potential transformer isolator. The selector arm 260= is now moved to the fourth position and. thekey 266 operated'. to` .bring the selector bar.

into the fourth position, and the yfinal operationp'is to depress the closing push 320 to cause the executive motorv tofdrive'the shaft 287 to,`

close the mainv circuit-breaker.V .Other opera-i tions canbe etIected asy may `berequired by suitableoperation ofr the control switches. In-

dicating lamps,.(not shown) '.are'provlded at theA control lpoint' withsuitable operatingl circuits to xgive theroperator 'anindication of the condition of the controlledvswitches.

-Wh`atwe claim rasour invention` and desire to secure by Letters Patent =is:- I

Ai'.-.In=c1ec;r1c switchgcar the combinationy or a `grouprofz-A switches associated with onaanother, Y' independently. I operable 'actuating levers respectively` :controlling the switches each lever having! an operative and an inoperative position a'selectorbarlongitudinally movable-into any of La number ofipositions,.andcooperating slots and projections onlthe'selector bar andthe actuating levers forpermittingfin each positiony of thebar only such lever l'actuation as will not cause con-I flictingfs'witchingconditions to be set up and forl 'preventing movement of the selector bar to any position unless the actuating 4levers are in posi-y tions appropriate to such movement, the arrangement being such-thatfat leastone of vthechanges ofpsition oi the selector-bar can be effected.

while one ofthe actuating levers is in its operativeposition andI another-*actuating lever in Set *up* andffor *preventing movement of. the/Se?,

' lector bar tol any position unless the actuating 1evers are inpositions appropriate to sucl'rmclve-vl ment, the arrangement being such that in'atleast vinoperative position.v Y

2. In" electric switchgear' theK combination 'of .a group 'of switches associated. with Lone another, actuating-v levers respectively controlling. rthe switches-each lever having an operative and an inoperativeposition, a commonv shaft on which the actuating levers are pivoted so vas to be operable independently of'one another, a selector bar a-position appropriate to such operation and to prevent movement of :the selector bar to any position unlessthe yactuating levers; are inr positions appropriate to-such movement, thearrangement beingsu'ch that at least one of the changes ofi'position of the rselector bar can be effected while oneof theactuating levers is in its operative yposition and another actuating lever inits inoperative position. l I

3f In electric switchgear group of switches associatedwith oneanother, in-

dependently operable actuating levers respectively.. controlling theswitches each lever havingl an operative and. anv inoperativerposition, a selector harlongitudinally movable intqany of a number of positions.and cooperating slots and projoctlonson the selector bar and the actuating levers whereby an'vactuating lever cannot be op-v erated -unless the ,selector bar has first been movedzinto-aipositon appropriate tosuch operathe combination of aA tion and the ,selector bar -canxictbel inovedinto theselected position unless vthe actuating;A levers are in positions` appropriate to such'movement,A the arrangement being such that in at least one ofthe positions 4ofdthe selector bar at least two ofthe actuating levers can be operated.

f4. Inelectric switchgear, the combination with a main circuit-breakerand auxiliary switches associatedi therewith, of.. interlockingv mechanism for the auxiliaryswitches comprisingr actuating leversfor the auxiliary switches, acommon shaft on ywhich the actuating levers are pivoted, a se-y lector bar disposed parallel 'to the shaft, preselecting means for moving the selector barlongitudinally, cooperating lslots and projections on the selector bar and the actuating levers which act to prevent operation of vany of the levers unless the selector bar is in a position appropriate tok such operation and -to prevent movement of the selector barunless the actuating levers are ,inl

a `position appropriate to such movement, and means whereby the selector bar prevents closing ofthe main circuit-breaker unless the auxiliaryr into any of a number of positions, and cooperating slots and projections on'the selector bar and thezactuating levers .for permitting in each position of the bar only suchlever actuation as will not cause conflicting switching conditions to be one of its positions the selector/bar can only be movedto a certain other position -when o ne of the actuating levers is. in its operativep'osition.V

6. In electric switchgear, the combination with a main circuit-breaker and auxiliary switches associated therewith,v of .interlockingk mechanism.'

for the auxiliary switches comprising actuating levers for the auxiliary switches, a common shaft,

on which the actuating. levers are pivoted,l a.

selector bar disposed .parallel to the shaft, preselecting means for moving the selector bar longitudinally in any ofv a number of positions, means whereby the selector bar acts'to permit or pre-A vent theactuation of the actuating levers in `accordance with itsposition, :two members respectively connected to the preselecting means and to the main circuit-breaker closing mechanism,

and; a; locking bar cooperating with such mem-v bers and actingV to lock `one o r. other of the members against movement in accordance with the position-of the othermember, the arrangement being such that the main circuit-breaker cannot be closed unless the auxiliary switches are4 in a condition appropriate-to such closing andy the selector bar is locked againstfrnovement so long as the main circuit-breaker is closed.

'1. In4 electric switchgear the .combination ci` a group of switches associated with one another,v

actuating levers respectively controlling the operation of the switches, a selector `bar longitudinally movable into iany, of.- a-.number of positions, means whereby, the selectorbaracts .to permit or prevent .actuation of the actuating. levers in accordancewith itsposition, oil-immersed electrical apparatus associated with the `controlled switcheaja removable oil tank containing such apparatusgancl means `whereby the selector bar prevents removal oftheA tankunless the switches are in acondition (to isolate `the apparatus in the tank. L l

..;8.,In electric switchgearfthe combination of ajgroup of switches associated .with one another, actuating levers respectively `controlling, the operation o f `the switches, aselector vbar `longitudinellyy movable into `any of a number ofpositions, .whereby theselector bar acts to permit onpreventactuationofthe actuating levers in accordance ,with its position, oil-immersed electrical apparatus associated `with the controlled switches,. .a removable oil tank containing such apmnjatus, and means wherebyfthe removal of tanktpreventsmov'ement of the selector bar. Q .Dran--electricswitchgear thecombination with amain'circuit-breaker and auxiliary switches associated therewitl i,. of `interlocking mechanism YLAmm'ising actuating..levers for the auxiliary switches, a common shaft .on which the actuatinglevers .are pivoted, a .selector bar .disposed parallel tolthelshaft,,.preselecting means for movythlef. selector bar "longitudinally, cooperating slotsandprojections onlthe selector bar and the aotuatin'gllevers whereby an actuating lever cannot be-loperated .unless .the selector bar has first been moved 'into -a .positionappropriate to such l operation .and the selector'bar cannot be moved intor.. th'e selected position unless the auxiliary switchesare .inja *condition appropriate to such movement, a lremovableoil tankcontaining the mainmircuit-breaker, and means whereby the selector ,bar prevents removal of the tank .unless the .auxiliaryrswitchesare in a condition to isolate-the main circuit-breaker. n

l lfInelectric switchgear the combination with ya group nf, switches associatedwith one another, actuatingleversfcontrolling the operation of the switchesla selector-fijan longitudinally .movable intoany of lanumber ofpositions, cooperating slots andlprdlectionsonithe selector bar and the actuating, vers-whereby an actuating lever cannot'befpperated unless the` selectorbar *hasA first beenmoved "into aposition appropriate 'to such operationgand the selector :bar cannot be moved into theltselected `position "unless the actuating levers arejin positions appropriate to such movement,^ioilimme`rsed apparatus `associated with the'controllel switches;` a` removable oil` tank containingsuch apparatus, means whereby the selector Abariprevents removal ofthe tank unless theif'auxiliaryswitchesiaredn a condition Vto isolate the. apparatus linthe tank;1andmeans wherebyf-the :selector Llbar is held against `movement mlo'ng'as ,thetank is removed.' j

711.-'.Inielectric switchgear ,the combination of a group of switches associated with one another,

f acti'ltinglevers respectively controlling the operation'fof;the'switches, a selector bar longitudinally movable into any of a number of positions, means whereby the selector bar acts to permit or prevent the actuation of the actuating levers in accordance with its position, an oil-immersed electrical apparatus associated with the controlled switches, a removable oil tank containingsuch apparatus, a slotted interlocking bar connected to the selector bar, a spring-pressed plunger, and means whereby on removal of. the

prevents removal of the tank unless the switches are in a condition to isolate the apparatusin'the tank.

13. The combination with the features set forth in claim 1 of an oil-immersed electrical apparatus associated with the controlled switches, a removable oil tank containing such apparatus, an electric coupling device controlling theremoval of the tank, and means whereby the selector bar prevents closing of l the coupling unless the switches arein a 'condition to isolate the apparatus in the tank.

14. In electric switchgear, the combination with a group of switches associated with one another, of interlocking mechanism for the switchescornprising actuating levers for the switches each movable from one operative position to another for the operation of the associated switch, a common shaft on which the actuating levers are pivoted, a longitudinally movable selector bar disposed parallel to the common shaft and transversely slotted` to permit movement of each actuating lever from one operative position to the other when the selector bar is in a position appropriate to such movement, preselecting means for moving the selector bar longitudinally, segmental extensions on the actuating levers having peripheral slots lying in the path of the selector bar in the operative positions of the levers, and projections on the selector bar cooperating with the slots in the segmental extensions of the levers to permit or prevent movement of the selector bar in accordance with the positions of .the actuating levers, the arrangement of the slots and projections being such as to prevent operation of a switch unless the selector bar is in a position appropriate to such operation and to `prevent movement of the selector bar into the selected position unless the switches are in a condition appropriate to such operation.

l5. In `electric switchgear the combination 'of a group of switches associated with one another, actuating levers respectively controlling the operation of the switches, a selector bar longitudinally movable into any of a number of operative positions, cooperatingslots and projections-on the selector bar. and the actuating leverswhich act to prevent operation of any of the levers unless the selector bar is inra position appropriate to such operation and t0 prevent movement ofthe selector bar 4.into any operative position unless the actuating levers are in positions appropriate to such movement, and means `whereby `the movements of the selector bar and of the actuating levers-can be controlled electrically.

16. `In electric switchgear the combination of a group of :switches associated with one another,actuating levers respectively controlling .the operationof thevswitches, a common shaft on which the actuating levers are pivoted, a selector bar "disments of the selector bar and of the actuating levers can be controlled electrically from a remote point or can alternatively be effected by direct manual operation.

17. The combination with the features set forth in claim 1, of means whereby the movements of the selector bar and of the actuating levers can be controlled electrically.

18. The combination with the features set forth in claim 1, of means whereby the movements of the selector bar and of the actuating levers can be controlled electrically from a remote point or can alternatively be effected by direct manual operation.

,19. The combinationy with the features set forth in claim 3, of means whereby the movements of the selector bar and of the actuating levers can be controlled electrically.

20. The combination with the features set forth in claim 1, of a reversible electricmotor for moving the selector bar, a second reversible electric motor, means controlled by the movements of the selector bar for selectively coupling the second motor to the actuating levers, and means for controlling the energization of the two motors.

21. The combination with the features set forth in claim 3, of a reversible electric motor for moving the selector bar, a second reversible electric motor, means controlled by the movements of the selector bar for selectively coupling the second motor to the actuating levers, and means for controlling thev energization of the two motors. y

22. The combination with the features set forth in claim 5, of a reversible electric motor for moving the selector bar, a second reversible electric motor, means controlled by the movements of the selector bar for selectively coupling the second motor to the actuating levers, and means for controlling the energization of the two motors.

' 23. The combination with the features vset forth in claim 14, of a reversible electric motor for moving the selector bar, a second reversible electric motor, means controlled by the movements of the selector bar for selectively coupling the second motor to the actuating levers, and

- means for controlling the energization of the two motors. f i

24. In electric switchgear the combination of a group of switches associated with one another, actuating levers respectively controlling the operation of the switches, a selector bar 'longitudinally movable into any of a number of positions, cooperating slots and projections on the selector bar and the actuating levers which act to prevent operation of any of the levers unless the selector bar is in a position appropriate to such operation and to prevent movement of the selector bar into any position unless the actuating levers are in positions appropriate to such movement, a reversible electric motor for moving the selector bar, a manually-operated selector switch at aremote point controlling the energization of the motor, a contact device operated by movement of the selector bar and acting both to determine the direction of rotation of the motor in accordance with the relation between the existing position of the selector bar and the desired new position thereof and to stop the motor when such new position has been reached, and means electrically controlled from the remote point for effecting operation of the actuating levers.

25. The combination with the features claim in claim 1 of a selecting reversible electric motor for moving the selector bar, an executive reversible electric motor, an actuating device for each actuating lever, means for connecting the executive #motor to such actuating devices, means whereby the engagement and disengagement of each actuating device with the associated actuating lever is controlled by the movements of the selector bar, and means for controlling the energization of the two motors.

26. In electric switchgear the combination of a group of switches associated with one another, actuating levers respectively controlling the operation of the switches, a selector bar longitudinally movable into any of a number of positions, cooperating slots and projections on the selector bar and the actuating levers which act to prevent operation of any of the levers unless the selector bar is in a position appropriate to such operation and'to prevent movement of the selector bar into any position unless the actuating levers are in positions appropriate to such movement, a reversible electric motor carried by the selector bar, a group of actuating devices for the actuating levers so carried by the selector bar as to be selectively brought into driving engagement with the associated actuating levers by the movements of the selectorbar, means for connecting the motor to the actuating devices, and meansr for controlling the energization of the motor.

27. The combination with the features set forth in claim 2, of means vwhereby the' movements of the selector bar and of the actuating levers can be effected by direct manual operation, and means whereby such movements can alternatively be controlled electrically from aremote point, said last-named means comprising a selecting reversible electric motor for moving the selector bar, a manually operated selector switch at the remote point, a contact device operated by the movement of the selector bar and cooperating with the remote selector switch to control the energization of the selecting motor whereby the selector bar is caused to move into a position determined by the operation of the remote switch provided that such movement is not prevented by the positions of the actuating levers, an executive reversible electric motor carried by the selector bar, means controlled by movements of the selector bar for selectively coupling the executive motor to the actuating levers, and manually operable switches at the remote point for controlling the energization of the executive motor.

- JOHN CHRISTIE. ALFRED DONKIN. 

